The combination of a gun and a surprise gone wrong left a beloved 18-year-old track star dead, authorities in Longmont, Colorado, say.

The incident happened Friday when Premila Lal and her 12-year-old cousin decided to play a joke on Nerrek Galley, a close family friend, according to Lal's father. The Lal family had recently moved, and Galley had been keeping an eye on the recently vacated home.

Lal and her cousin snuck into the house just before 8 p.m. unbeknownst to Galley, who was playing video games with Premila's 15-year-old brother, Pranil.